Using `variableAccessedAsValue` fixes a FP because we can now
distinguish modifications to the parameter from modifications to data
_reachable from_ the parameter.
The previous reccomentation changed the behaviour of the code.
A user following the advice might have broken her/his code:
With call-by-value, the original parameter is not changed.
With a call-by-reference, however, it may be changed. To be sure,
nothing breaks by blindly following the advice, suggest to pass a
const reference.
